A tapered endodontic rotary file for shaping or cleaning a root canal in a tooth has one or more flutes spiraling along the length of the file. The diameters of the one or more flutes tapers in a non-uniform manner from a first diameter in a shank portion of the file to a smaller diameter in a tip portion of the file such that at least one flute region intermediate the shank portion and the tip portion has a diameter less than a straight line taper from the shank portion to the tip portion. The flutes can also be landed and the width of the lands can be varied along the length of the file. In particular, the width of the lands in the intermediate region are wider than the width in the tip or shank portion.
